1) The document discusses nutrients and their importance for organisms. It focuses on carbohydrates, fats, and proteins.
2) Carbohydrates include sugars, starches, and fibers and serve as energy sources. They are broken down through hydrolysis. Fats also provide energy and insulation. Proteins are made of amino acids and are essential for growth and repair.
3) Tests are described to identify carbohydrates, sugars, and fats in food. The properties and functions of nutrients are explained at the molecular level.
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Topic 3 chapter 4 part 1 nutrients - full
1. Topic 3: Chapter 4
NutrientsNutrients –– Part 1Part 1
The needThe need
for foodfor food
++
CarbohydraCarbohydra
2. Chemicals and Reactions that
take place in the cell.
• Living organisms contains huge amount of
Macromolecules (large molecules)
• Chemical activities that take place in a cell is
known as metabolism.
• Metabolic reactions are categorized as anabolic
reactions and catabolic reactions.
3. Anabolic & Catabolic
Reactions
• Anabolic reactions build up large molecules
from simple molecules.
• Catabolic reactions break down larger
molecules into smaller molecules.
4. Illustration of Anabolic &
Catabolic Reactions
H20 Nitrate Phosphate
Sunlight
CO2
Carbohydrates
(e.g. Glucose)
Photosynthesis
5. Illustration of Anabolic &
Catabolic Reactions
Nitrate Phosphate
Lipids
Carbohydrates
(e.g. Glucose)
Protein
Eat
Digestion
Absorption
6. Why do organisms need
food?
1) To provide energy for the vital activities of
the body via respiration.
Physical movement, Digestion, Excretion, etc.
2) To synthesize new protoplasm – for growth
& repair, & for reproduction.
3) To maintain good health – prevent
deficiency disease.
Vit. C, Calcium, etc.
7. Nutrients
• Chemical substances in food that nourish the body.
• They provide energy & raw materials needed by
the body.
(A) Organic Nutrients(A) Organic Nutrients
(Contains Carbon)(Contains Carbon)
(A) Organic Nutrients(A) Organic Nutrients
(Contains Carbon)(Contains Carbon)
(B) Inorganic Nutrients(B) Inorganic Nutrients
(does not contain Carbon)(does not contain Carbon)
(B) Inorganic Nutrients(B) Inorganic Nutrients
(does not contain Carbon)(does not contain Carbon)
1)1) CarbohydratesCarbohydrates
2)2) FatsFats
3)3) ProteinsProteins
4)4) VitaminsVitamins
5)5) Dietary FibreDietary Fibre
1)1) WaterWater
2)2) Mineral SaltsMineral Salts
8. A(1): Carbohydrates
• Organic compounds made up of the
elements carbon (C), hydrogen (H) &
oxygen (O).
• The hydrogen & oxygen atoms are
present in the ratio 2:1.
• Generalized formula: CnH2mOm.
9. A(1): Functions of Carbohydrates
a) as a substrate for respiration
provide energy for cell activities
a) to form supporting structures
e.g. plant cell walls
a) to be converted to other organic compounds
such as amino acids and fats
b) for the formation of nucleic acid
e.g. DNA
a) to synthesize lubricants
e.g. mucus – Carbo + Protein)
a) to produce the nectar in some flowers
10. A(1): Sources of Carbohydrates
•Broken down quickly to provide
energy for the body
• Found naturally in food (Fruits,
Milk, etc.)
• Found in processed or refined
food ( Candy, Syrup, etc.)
•Lack Vitamins, Minerals & Fibres
•Made of sugar molecules strung
together in long complex chains
• Majority of carbohydrates are
from complex carbohydrates
and naturally occurring sugars.
•Provides Vitamins, Minerals &
Fibres
11. A(1): Groups of Carbohydrates
CarbohydratesCarbohydrates
Polysaccharides
(complex carbohydrates)
Polysaccharides
(complex carbohydrates)
Disaccharides
(double sugars)
Disaccharides
(double sugars)
Monosaccharides
(single sugars)
Monosaccharides
(single sugars)
e.g. glucose
fructose,
galactose
e.g. glucose
fructose,
galactose
e.g. starch,
glycogen,
cellulose
e.g. starch,
glycogen,
cellulose
e.g. Sucrose,
Maltose,
Lactose
e.g. Sucrose,
Maltose,
Lactose
12. • Simple sugars, sweet
• Smallest basic unit.
• ALL with general formula C6H12O6.
- But differ in arrangement of atoms in
molecules.
Monosaccharides
(single sugars)
Monosaccharides
(single sugars)
14. Condensation
• Chemical reaction in
which
• A water molecule is
needed
• to break up a complex
molecule into smaller
molecules
• Chemical reaction in
which
• A water molecule is
needed
• to break up a complex
molecule into smaller
molecules
• Chemical reaction in
which
• 2 simple molecules are
joined together to
form a larger molecule
• with the removal of
water
• Chemical reaction in
which
• 2 simple molecules are
joined together to
form a larger molecule
• with the removal of
water
Hydrolysis
15. Condensation: Formation of
LactoseLactose
• occurs naturally in milk (milk sugar).
• broken down by the enzyme “lactase” during
digestion to yield glucose and galactose by hydrolysis
• When milk sours, bacteria converts lactose to lactic
acid
16. Condensation: Formation of
Maltas
e
Maltas
e
• Malt Sugar
• Important component in the process of fermenting
barley that can be used for brewing beer.
• broken down by the enzyme “maltase” during
digestion to yield 2 glucose molecules by hydrolysis
18. Hydrolysis: Breaking down of
Sucros
e
Sucros
e
+
enzyme
glucose fructosesucrose water
+
• broken down by the enzyme “sucrase” /
“invertase” during digestion to yield glucose and
fructose by hydrolysis
23. Storage Glucose
• Starch
• Stored in leaves, tubers and roots
Plants
Animals
• Gycogen
• Stored mainly in liver and muscles
24. Glycogen and Starch
as storage materials
• Insoluble in water
do not change the water potential in cells
• Large molecules
Unable to diffuse through cell membranes
• Easily hydrolysed to glucose when needed
e.g for tissue respiration
• Compact shapes which occupies less space.
25. Hydrolysis and Condensation
maltase maltase maltase maltase
Starch (in plants)Starch (in plants)
MaltoseMaltose
GlucoseGlucose
Hydrolysis in the
mouth
Hydrolysis in the guts
by enzyme maltase
Condensation in the liver
Glycogen (in animals)Glycogen (in animals)
Consumed and
undergoes
Digestion
Digestion
Glucogenesis
26. Food Test (1)Food Test (1)
Test for Starch – Iodine TestTest for Starch – Iodine Test
Procedure:
• Add 1-3 drops of iodine solution onto any
substance.
Results:
• If starch is present, the iodine solution
changes from yellowish brown to blue-black
colour.
27. Food Test (2)Food Test (2)
Test for Reducing Sugars – Benedict’sTest for Reducing Sugars – Benedict’s
TestTest
Reducing Sugars:Reducing Sugars:
Glucose, Fructose, Maltose, Lactose
Procedure:Procedure:
1. Add 2 cm3
of Benedict’s solution to
equal volume of test solution.
2. Mix the solutions by shaking.
3. Heat the mixture in a boiling water-
bath for 5 minutes.
4. Prepare a control using distilled water
instead of the test solution Benedict’s solution
28. Food Test (2)Food Test (2)
Test for Reducing Sugars – Benedict’sTest for Reducing Sugars – Benedict’s
TestTest
Results
Colour change
Amount of reducing sugar
present
blue to green mixture trace amount
blue to yellow / orange
precipitate
moderate amount
blue to brick-red
precipitate
large amount
29. Food Test (2)Food Test (2)
Test for Reducing Sugars – Benedict’sTest for Reducing Sugars – Benedict’s
TestTest
Results
Positive Benedict’s test Negative Benedict’s test
Brick Red
Precipitate
Blue
solution
32. A(2): FATS
• Organic compounds made up of the
elements carbon (C), hydrogen (H) & oxygen
(O).
• but unlike carbohydrates, they contain much
less oxygen in proportion to hydrogen. (E.g.
Beef Fat: Tristearin – C57H110O6)
• No General formula for fats
33. A(2): Composition of a Fat
Molecule
• A fat molecule is made up of four parts:
- 1 molecule of glycerol
- 3 fatty acid chains
Glycerol
Fatty
Acids
34. A(2): Breaking down fats
Hydrolysi
s
Hydrolysi
s
• The breaking down of 1 fat molecule involves the
addition of 3 water molecules to form 1 glycerol and
3 fatty acid molecules IN THE PRESENCE OF AN
ENZYME (Lipase)
36. A(2): Groups of Fats
FatsFats
Unsaturated FatsUnsaturated FatsSaturated FatsSaturated Fats
37. A(2):
• Found mostly in animals
• Fatty acids are straight
chains
• Most are solid at room
temperature (e.g butter)
• Cholesterol usually found
with polysaturated fats
Increases risk of Coronary
Heart Diseases & Gall stone
formation
Saturated FatsSaturated Fats
38. • Found mostly in vegetables
(except Coconut and Palm Oil)
• Fatty acids are bent in some
places
• Most are liquid at room
temperature (e.g Olive Oil)
• Fatty acid chains contains double
bonds and are able to take in 1 or
more pairs of H-atoms
• Hydrogenation of unsaturated
fats Trans-fat
A(1): Unsaturated FatsUnsaturated Fats
40. A(1): Functions Fats
a) as a source and store of energy
b) Insulating material (Prevents excessive heat
loss)
e.g layer of blubber beneath the skin of whales
a) Solvent for fat-soluble substances
some vitamins and vital substances (e.g hormones)
d) Essential part of the protoplasm
e.g cell membrane (Phospholipds and cholesterol)
e) A way to reduce water loss from the skin
surface
41. Food Test (3)Food Test (3)
Test for Fats – Alcohol EmulsionTest for Fats – Alcohol Emulsion
TestTest
Procedure:
Add 2 cm3
of ethanol to the test solution and
shake the mixture thoroughly for 5 minutes.
Observe for changes.
Add 2 cm3
of water to the mixture and shake
the mixture. Observe for changes.
Liquid Food
42. Food Test (3)Food Test (3)
Test for Fats – Alcohol EmulsionTest for Fats – Alcohol Emulsion
TestTest
Procedure:
Cut the sample into small pieces and place
them in a test tube.
Add 2cm3
of ethanol and shake thoroughly.
Allow the solid particles to settle. Decant the
ethanol into another test tube containing 2cm3
of water. Make observations.
Solid Food
43. Food Test (3)Food Test (3)
Test for Fats – Alcohol EmulsionTest for Fats – Alcohol Emulsion
TestTest
Results:
A white emulsion is formed if fats is present
white
emulsio
n
46. A(3): Proteins
• Are very large complex organic moluecules
containing carbon (C), hydrogen (H), oxygen
(O) and nitrogen (N). Sometimes, Sulfur (S)
and Phosphorus (P)
• E.g. Insulin: C254H317O75N65S6
• Made up of basic small units called amino
acids
48. A(3): General Structure of an
amino acid
• A fat molecule is made up of four parts:
- 1 Amino Acid group (-NH2)
- 1 Acidic Group (-COOH)
- 1 Side Chain (denoted by R)
Can be:
•Sulfur (S)
•Acidic groups (-COOH)
•Amino groups (--NH2)
and/or
•Hydroxyl groups (-OH)
49. A(3): Why is there a need for so
many different R-groups?
• The R-Group determines the type of
amino acid formed.
• There are 20 naturally occuring amino acid:
• Examples –
• Leucine, Valine, Glutamine:
• 8 Essential a.a: Cannot be synthesized by the
body. Must be obtained through the diet
• 12 Non-Essential a.a: Can be synthesized by
the body
50. A(3): Synthesis of Proteins
• The bond between 2 amino acids is called: Peptide Bond
• Many amino acids link together by peptide bonds to form a
polypeptide chain / peptone
Condensatio
n
Condensatio
n
51. amino acids polypeptides Protein molecule
A(3): Synthesis of Proteins
Primary / Secondary
Structure
Primary / Secondary
Structure
Tertiary
Structure
Tertiary
Structure
Amino acids are
linked by
peptide bonds
to form
polypeptide
chains
Amino acids are
linked by
peptide bonds
to form
polypeptide
chains
Polypeptide
chains coil and
fold around each
other to form a
3-d structure
held by weak
H-bonds
Polypeptide
chains coil and
fold around each
other to form a
3-d structure
held by weak
H-bonds
52. Different proteins have a different
sequence of A.A
A.A sequence determines the
bonds formed and the structure of
the protein.
Different proteins with different
structures perform different
functions.
Weak H-bonds can be easily
broken by:
• Heat
• Chemicals like Acid and Alkalis
Protein loses its structure
and function (is
DENATURED)
Different proteins have a different
sequence of A.A
A.A sequence determines the
bonds formed and the structure of
the protein.
Different proteins with different
structures perform different
functions.
Weak H-bonds can be easily
broken by:
• Heat
• Chemicals like Acid and Alkalis
Protein loses its structure
and function (is
DENATURED)
Structure VS FunctionStructure VS Function
53. A(3): Digestion of Proteins
polypeptides
amino acids
protein
hydrolysis (digestion)
hydrolysis (digestion)
Protein molecules are too
large to pass through the cell
membranes
Smaller and simpler A.A
molecules are soluble in
water and can pass
through the cell membrane
into the cells to synthesize
new proteins
55. A(1): Functions Proteins
a) Formation of new protoplasm
for growth & repair of worn-out body parts/ cells
b) Synthesis of enzymes and hormones
e.g digestive enzymes and insulin / sex and
growth hormones
b) Formation of antibodies to combat diseases
d) Can be source of energy
56. Food Test (4)Food Test (4)
Test for Proteins – Biuret TestTest for Proteins – Biuret Test
Procedure:
Add 1 cm3
of sodium hydroxide solution to the
2 cm3
of test solution. Shake thoroughly.
Add 1% copper (II) sulphate solution, drop by
drop, shaking after each drop.
ALTERNATIVELY
Add 2cm3
of test solution to an equal volume
of Biuret solution. Shake well and allow the
mixture to stand for 5 minutes.
57. Food Test (4)Food Test (4)
Test for Proteins – Biuret TestTest for Proteins – Biuret Test
Results:
A violet colouration is
formed if proteins is
present
positive test
for protein
positive test
for protein